[1] Hokusuikai Kinen Hosp, Dept Urol, 3-2-1 Higashihara Cyo, Mito, Ibaraki 3100035, Japan
[2] Kameda Med Ctr, Dept Urol, Chiba, Japan
[3] Univ Tsukuba Hosp, Dept Urol, Ibaraki, Japan
[4] Jichi Med Univ, Dept Urol, Saitama Med Ctr, Saitama, Japan
[5] Eastern Oomiya Med Ctr, Dept Urol, Saitama, Japan
[6] Hokusuikai Kinen Hosp, Dept Orthopaed Surg, Ibaraki, Japan